Manipulation of polycrystalline TiO2 carrier concentration via electrically active native defects
(a) XPS survey spectrum of undoped TiO2 surface with Ti, O, C, and substrate peaks labeled and (b) comparison between C 1s peak prior to and after Ar ion sputtering.
Room temperature XRD spectra obtained with a Cu Kα1 primary x-ray beam for (a) 100 nm TiO2/20 min anneal, (b) 100 nm TiO2/24 h anneal, and (c) 300 nm TiO2/20 min anneal with corresponding cross-sectional SEM images.
Temperature-dependent XRD spectra obtained with a Cu Kα primary x-ray beam for 100 nm TiO2 where a scan was acquired instantaneously after ramping to 550 °C (45 °C/min) and then once per hour while at 550 °C (1 h, 19 h shown here). Peak intensity and area change minimally after the instantaneous scan at 550 °C.
Average crystallite size obtained by room temperature XRD peak fitting vs (a) film thickness and (b) annealing time at 550 °C (100 nm TiO2); also, bulk density obtained from XRR spectra fitting vs (c) film thickness for 20 min annealing time at 550 °C, (d) film thickness for 24 h annealing time at 550 °C, and (e) annealing time at 550 °C (100 nm TiO2).
Nd vs film thickness for (a) anatase TiO2 annealed at 550 °C for 20 min and (b) anatase TiO2 annealed at 550 °C for 24 h. Data for e-beam evaporated anatase TiO2 from Ref. 21 are shown in (b) for purposes of comparison. Nd values and corresponding error bars were obtained by averaging three distinct data sets acquired 1 week apart. All samples were stored in dark.
Nd vs annealing time at 550 °C for 100 nm anatase TiO2. Nd values and corresponding error bars were obtained by averaging two distinct data sets acquired 1 week apart. All samples were stored in dark.
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